1. Field of the Invention
This invention relates to machine tools and more particularly to work piece supporting roller members for work tables.
2. Prior Art
Machine tool such as punches and the like are generally equipped with work tables on which a work piece, such as a mass or sheet of metal is supported and on which it may be moved to properly position it with respect to the tool which is to act upon it.
The rollers are primarily antifriction devices which are designed to allow ease of movement of the work piece on the work table. To this end, the roller normally constitutes a ball or other rolling element which is received in a housing which encloses a portion of the rolling element and from which the work piece contacting portion of the rolling element projects. In those cases where the rolling element is a ball, the ball is generally submerged below its diameter in the housing and is retained in the housing by means of an opening in the housing through which the ball projects, the opening having a diameter less than the full diameter of the ball. Permanent lubricating means or other features may be provided in the housing with the rolling element being supported in the housing in such a manner as to allow it to turn within the housing in a relatively friction free manner.
Heretofore, the roller assemblies which include the roller member, its affiliated housing, and any internal mechanisms, were attached to the work table in a permanent manner such as by welding or the like. It has also been known to use envelope type work tables with the roller members entrapped between parallel top and bottom table defining sheets. Since a relatively large number of such roller members are required for each work table, the prior methods of attachment were expensive, labor intensive and, in general, unsatisfactory.
Additionally, because of damage or for other reasons, it sometimes became desirable to replace such roller members. However, heretofore, the roller members, because of their permanent attachment, were for all practical purposes impossible to replace. It would therefore be an advance in the art to provide a simplified means of attaching the roller members to the work table, which means and apparatus reduces the expense of attaching the roller members while at the same time allowing replacement if necessary.